access to time or current frame in OSL
To access the frame info you could create a simple OSL script:

shader frame_node(
    int  frame= 1,
    color Color1 = color(0.8, 0.0, 0.0),
    output color Diffuse = 0)
{
    Diffuse = frame * Color1;
}


and keyframe the frame input socket accordingly. 
e.g.: